Conventional image-forming devices, such as various printers and facsimile machines, generally include a sheet-feeding cassette accommodating a stack of sheets of paper or other recording medium, and the paper is fed to a recording unit one sheet at a time to be formed with images thereon. In order to form images on different types of sheets, a plurality of sheet-feeding cassettes for respective types of sheets may be attached to a main body of the image-forming device.
For example, in Japanese Patent-Application Publication No. HEI-11-599925, a flat plate-shaped second sheet-feeding cassette can be detachably disposed on a substantially box-shaped first sheet-feeding cassette so as to accommodate smaller sheets than those in the first sheet-feeding cassette therein. In this configuration, larger sheets can be accommodated in the first sheet-feeding cassette, and smaller sheets can be accommodated in the second sheet-feeding cassette. Only the first sheet-feeding cassette is attached to a main body of the image-forming device when the sheets in the first sheet-feeding cassette are to be used, and the first sheet-feeding cassette is attached to the main body of the image-forming device while the second sheet-feeding cassette is mounted on a sheet mounting surface of the first sheet-feeding cassette when the sheets in the second sheet-feeding cassette are to be used.
However, in this configuration, since the second sheet-feeding cassette is mounted on the sheet mounting surface of the first sheet-feeding cassette, the second sheet-feeding cassette must be detached each time the first sheet-feeding cassette is used after the second sheet-feeding cassette was used, and the second sheet-feeding cassette must be mounted each time the second sheet-feeding cassette is used after the first sheet-feeding cassette was used. In other words, the sheets in the first sheet-feeding cassette cannot be fed in the state where the second sheet-feeding cassette is mounted on the first sheet-feeding cassette. For example, a user may wish to perform trial print for confirming the position of an image and the state of color by forming the image on ordinary paper stored in the first sheet-feeding cassette prior to formally forming the image on a postcard accommodated in the second sheet-feeding cassette. In this case, the user needs to detach the second sheet-feeding cassette from the first sheet-feeding cassette for the trial print. Thus, although the two sheet-feeding cassettes can be attached to the main body of the image-forming device, the sheet (sheet-feeding cassette) to be used needs to be replaced each time. The procedure to form images therefore becomes complicated.
Also, it is necessary to detach the second sheet-feeding cassette and to place the same at a separate position if only the first sheet-feeding cassette is used for a long time. Thus, a storage place is needed for the second sheet-feeding cassette, and there is a danger that the detached second sheet-feeding cassette is lost. Furthermore, since the second sheet-feeding cassette is detachably mounted on the first sheet-feeding cassette, an operation of correctly positioning the second sheet-feeding cassette on the first sheet-feeding cassette is complicated.
A first sheet-feeding cassette and a second sheet-feeding cassette disclosed in Japanese Patent-Application Publication No. HEI-11-314773 are stacked one on the other with a partition wall interposed therebetween, and are attached to a main body of an image-forming device. The first and second sheet-feeding cassettes are both shaped like a box and have the same configuration. Only sheets in an upper one of the first and second sheet-feeding cassettes contact a sheet feeding roller. In this configuration, the first and second sheet-feeding cassettes are attached to the main body such that the first sheet-feeding cassette is disposed on top of the second sheet-feeding cassette when sheets in the first sheet-feeding cassette are used, and the second sheet-feeding cassette is disposed on top of the first sheet-feeding cassette when sheets in the second feeding cassette are used. These stacked sheet-feeding cassettes are coupled to each other with a hinge having a center shaft on one side of a stack surface. By pivoting the first or second sheet-feeding cassette about the hinge to open to the outside, sheets can be supplied to the sheet supply cassette.
With this configuration, since the first and second sheet-feeding cassettes are coupled to each other with the hinge, it is unnecessary to position the two sheet-feeding cassettes with respect to each other, and there is no danger that the sheet-feeding cassettes are lost. However, in this configuration, in order to change the sheets to be used, a user needs to first detach the two sheet-feeding cassettes stacked one on the other from the main body of the image-forming device, turn the sheet-feeding cassettes upside down to interchange the vertical positions of the sheet-feeding cassettes, and then reattach the same to the main body. That is, as in Japanese Patent-Application Publication No. HEI-11-599925 described above, the sheet-feeding cassettes need to be detached each time the sheets to be used are changed, complicating operations for forming images.